The primary objective is to assess the effect of corticosteroid therapy in sarcoidosis. The pathologic process and the associated physiological impairment of lung function or other organ function are improved by corticosteroid therapy on short-term observations. It is not established whether these immediate beneficial results exert a prolonged effect and prevent any residual and continued impairment of structure and function of the lung. The design of the study is double-blind using steroid and placebo as therapy. Clinical and physiological studies are made at intervals and a final assessment made at five years. Additional areas of study are made from the available clinical material and include the incidence and diagnostic value of serum levels of converting enzyme for angiotensin, the population of T cells in sarcodosis and tissue typing for the prevalence associated with sarcoidosis. Exercise studies are made for use in assessing viability and as a further method of classification of sarcoidosis.